The Shaanxi provincial government said Wednesday the attacks had plagued not only the city of Ankang, where 19 died, as reported by the official Xinhua News Agency, but had killed 22 others in two adjacent cities.

The provincial government says it has mobilized a special medic team and trained more medical personnel to treat victims.

It says hornets mate and migrate in September and October when they are most aggressive in behavior. Local officials have also said weather changes may have contributed to the ferocity of attacks.

Authorities are warning residents to stay out of open fields and woooded areas to avoid contact with the Asian giant hornets (Vespa mandarinia) — the world’s largest hornet species with a 3-inch wingspan, a 2-inch body, and a quarter-inch-long stinger that delivers venom that contains a potent neurotoxin.

A man who was stung this week while harvesting rice said the hornets were relentless.

"I ran and shouted for help, but the hornets chased me about 200 meters, and stung me for more than 3 minutes," Chen Changlin recounted to the state-run China Youth Daily.

Chen said the hornets attacked him after swarming a woman and child who ran to him for help. They later died from their stings.

Outrunning the hornets is not an option as they can travel up to 25 mph and fly more than 60 miles daily.

Earlier this month, 23 children were stung in their heads, necks, hands and feet.

The Asian killer hornets “are formidable killers” when it comes to attacking other insects, according to the nonprofit Honeybee Conservancy.